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The NTSB gave new details on the comprehensive investigation being conducted at the site of yesterday's bus crash in Orland, Calif., on Friday, including news that authorities will preserve the crash wreckage for a thorough investigation. Patrick Healy reports from the site of the press conference in Red Bluff, CA for the NBC4 News at 5 and 6 p.m. on Friday, April 11, 2014. (Published Saturday, April 12, 2014)

The National Transportation Safety Board said Friday it would "not be speculating about probable cause" of a deadly bus crash in Northern California that took the lives of 10 people, most of whom were from Southern California.

Investigators said during a press conference that it would be working to collect information for at least the next one to two weeks depending on what they find.

“(We) don’t have a lot of factual information. It’s very, very early in the investigation still," said Mark Rosekind of the NTSB. "It's really important to acknowledge we won't be speculating about probable cause."

Those killed included five students and five adults who were traveling to Humboldt State University for a campus visit. Thirty-one victims were hospitalized after the crash. Their injuries ranged from critical to minor, CHP officials said.

Rosekind said they're hoping to find data that would have monitored drivers of both the FedEx and tour bus drivers, such as cameras looking forward toward the road and into the interior of the vehicles, but it's not clear if that even exists.

One of NTSB's challenges will be gathering consistent witness information, as details about the crash have been given to numerous different agencies that still need to collaborate, Rosekind said.

Survivors told the investigator the tour bus driver saw the FedEx truck coming toward it and honked the horn seconds before impact.

The side windows of the tour bus would not open as passengers tried to break out; the rear windows did open, investigators said.

A final report on the crash might take up to six months, according to the CHP.

"Since these are such in-depth, detailed investigations, we don't expect to have a final report for a minimum of three months, 90 days," said CHP Lt. Scott Fredrick. "It could take as long as six months depending on what the investigation entails."

Passengers described a "surreal" scene as people kicked out bus windows to escape the fire and smoke after the crash.

Two other buses that were part of the campus trip were not involved in the crash.

An autopsy will determine whether the driver of the FedEx truck had a medical condition or was deceased before the accident. The bus belonged to Silverado Stages, a tour bus company based out of San Luis Obispo.